Fix "lxc: Can not start unprivileged LXC containers with 4.18 kernel"
After kernel update to 4.18 it is not possible anymore to start unprivileged LXC containers.
Cf. https://bugs.debian.org/908223
Christian Brauner kindly backported the patch as needed to be applied on top of 2.0.9 in https://bugs.debian.org/908223#41 .